The invention relates to a data storing device for the storing of picture data in a compressed or decompressed data format in a data memory, the data storing device having a compression coding and/or decoding device.
Furthermore the invention relates to a method for storing picture data in a compressed or decompressed data format in a data memory.
Traffic monitoring installations are used to detect traffic violations such as speeding or crossing a red traffic light. Such traffic monitoring installations take a picture of each violator or his car during the violation. Due to the high amount of violators, a large number of pictures have to be processed. Conventionally, the pictures are recorded on film negatives (see U.S. Pat. Nos. 3,849,784; 3,858,223; 3,866,165; 4,887,080; 5,041,828). The operator is often faced with large quantities of films, which are difficult to process and evaluate.
In order to facilitate processing of the pictures, digital cameras have been used in such traffic monitoring installations (see U.S. Pat. No. 5,948,038). Such digital cameras offer the advantage that the digital data can directly be processed. Such digital cameras do not require any film negative. Therefore, it is not necessary to develop a film. In addition, evaluating and processing of the data is facilitated. Further savings can be achieved by automating the writing and sending out of the violation tickets. Nevertheless, also such traffic monitoring installations have capacity limits with respect to the quantity of pictures to be stored and processed.
It is known to reflect information onto the film negatives (U.S. Pat. No. 3,603,227; U.S. Pat. No. 4,988,994). In a corresponding way digital information blocks are added to the digital pictures, for example information about time and date.
In the art of digital picture processing, various methods of picture compression are known. Compression formats are known, in which a picture is compressed and the original state is restored, when the picture is decompressed.
Various methods are used for the compression of digital pictures. Examples of such methods are JPEG-, GIF, and TIF- formats, which are often used in the internet for the transmission of pictures. Such compression methods are mostly standardized, described in the respective literature and well known to a person skilled in the art. Examples of literature describing the various compression methods are: the book by Günther Born “Referenzhandbuch Dateiformate” Addison-Wesley publisher, 2nd revised edition 1992, ISBN 2-89319-446-0/VVA-Nr. 563-00446-4; and the standard IS 10918-1 ITU-T.81). Therefore, these compression methods need not be described in detail. The compression methods are also successfully used in traffic monitoring installations with a digital camera, in order to reduce the quantity of data.
In all these compression methods, the entire digital picture is compressed and, accordingly, the entire picture is decompressed. The disadvantage thereof is that, always the entire picture has to be decompressed, even if only a certain section of the picture or a certain block of information is needed,. Consequently the procedure is very slow.